abstract
The photocatalytic activity of titania nano/microparticles (nT and mT) and zinc oxide microparticles (mZ) as well as the rheological behavior of cement pastes with the addition of those particles were evaluated applying design of experiments (DoE). Such additives ranged from 0 to 1.2 wt.% in the cement paste, while the water/cement ratio (0.45) and superplasticizer (0.45 wt.%) remained invariable. Thus, pure blends and binary or ternary mixtures were studied. Pure blends containing nT or mT and ternary mixtures 0.67mT:0.17nT:0.17mZ reached the best and comparable performances in terms of photocatalytic activity. The theological parameters (plastic viscosity and yield stress) values changed along time in distinct levels described by a quadratic model. Samples with nT became less fluid, and the yield stress was the main rheological parameter affected. The kinetics of hydration was not significantly affected by additions up to 120 min testing, but showed noticeable distinctions for longer periods: mZ (delayed) and nT (shortened), while mT required about the same time to reach the maximum exothermic peak than reference paste. (C) 2014 Elsevier Ltd. All rights reserved.
keywords
SELF-COMPACTING CONCRETE; BUILDING-MATERIALS; TITANIUM-DIOXIDE; CERAMIC TILES; ORANGE II; DEGRADATION; MORTARS; NANOPARTICLES; DECOLORATION; CONSTRUCTION
subject category
Construction & Building Technology; Engineering; Materials Science
authors
Senff, L; Tobaldi, DM; Lemes-Rachadel, P; Labrincha, JA; Hotza, D
our authors
David Maria Tobaldi
Researcher
João António Labrincha Baptista
Full professoracknowledgements
The authors acknowledge the financial support of the Brazilian agency CNPq (National Council for Scientific and Technological Development). The authors also thank BASF for providing raw materials. D.M. Tobaldi is grateful to the ECO-SEE project (European Union's Seventh Framework Programme funding, grant agreement no 609234).